Fan



June 14, 1938. w, A EI E 2,120,780

FAN

Filed Jan. 20, 1934 gwwmtoz Patented June 14, 1938 PATENT OFFICE FANWalter A. Geise, Flint, Mich., assignor to General Motors Corporation,Detroit, Mich, a corporation of Delaware Application January 20, 1934,Serial No. 707,493

3 Claims.

I have found that the noise which is produced as the result of theoperation of the propelling engine of an automotive vehicle may becorisiderably reduced or, at least, rendered much less apparent orobjectionable by so constructing and/or arranging the blades of theengine cooling fan that one of them imparts to the air an impulse whosecharacteristics diiler from that imparted to the air by another bladeor, to be more specific, by making the angular pitch and/or the sizeand/or the shape of one of the blades different from that of anotherblade.

My invention may be embodied in multi-blade fans which have even oruneven numbers of blades; and in either type of fan, the angular pitchand/or the size and/or the shape of one blade may be different from theangularpitch and/or the size and/or the shape of the other blade orblades or the angular pitch and/or the size and/or the shape of oneblade may be different from the angular pitch and/or the size and/or theshape of another blade or blades but the same as the angular pitchand/or the size and/or the shape of still another blade or blades.

For a better understandingmf the nature and.

objects of the present invention, reference is made to the followingspecification in which there are described the preferred embodiments ofmy invention which are illustrated in the accompanying drawing, inwhich: 1

Figure 1 is a fragmentary side elevation of the front end of anautomotivevehicle in which is installed an engine cooling fan in whichisem bodied my invention.

Figure 2 is a front elevation of the engine cool ing fan which is shownin Figure 1.

In Figure 3, A-A, B-B, C-C andD-D indicate, respectively, sections onthe lines A-A,

B-"'B, C-C and DD of Figure 2.

Figures 4 and 5 are, respectively, a side ale-'- vation and a frontelevation of another engine cooling fan in which my invention isembodied.

In the drawing, the reference character 9 indigates the water coolingradiator of an automotive vehicle and the reference character lo thepropelling engine thereof. To draw cooling air through the radiator andforce it over the engine, there is provided a fan H which is arranged tobe driven through any ordinary or suitable mechanism by the engine It.

'I'he'fan H, which is shown in Figures 1, 2 an 3, consists of a hub I2on which there are mounted equi-angularly around the axis of rotation ofthe fan four propeller or screw typefan blades l3, l4, l5 and Hi whichmay be of the same size and shape or of different sizes and/or shapesbut, as Figure 3 clearly shows, have different angular pitches. The fanl'l, which is shown in Figures 4 and 5, consists of a hub it to whichthere is secured a spider I9 on which 5 there are mounted equi-angularlyaround the axis of rotation of the fan four propeller or screw type fanblades 20, 2|, 22 and 23 which may have the same or different angularpitches but are,- as Figure 5 clearly shows, of difierent sizes and/orshapes.

What angular pitches and/or sizes and/or shapes the several blades of afan in which my invention is embodied should be given to produce a fanwhich gives the most highly satisiactory results may be determined byexperiment. However, it should here be noted that the fan which willoperate most satisfactorily in one installation is not necessarily thefan which will operate most satisfactorily in another installation and,consequently, that since, practically speaking, what is to be consideredis not how quietly the fan operates when divorced from its intendedsurroundings, but how quietly the installation as a whole is when thefan is operat- 5 ing, the experiments should be conducted with :the fanincorporated in the installation in which it is intended to be used andthe most highly satisfactory results should be considered to have beenattained when the installation as a whole is most quiet when the fan isoperating.

To eliminate the possibility of a misunderstanding of what has been saidin the next preceding paragraph, I should, perhaps, point out that it isnot necessary by experiment to design a fan for each example of aninstallation, since when a fan suitable for a particular example ofaninstallation has been produced, similar fans may, without'furthe'rexperimentation, be satisfactorily 40 employed in all examples of thatinstallation.

Although I have shown and described as preferred embodiments of myinvention four-blade fans, it will be understood that the principlesunderlying my invention may be incorporated in 5 fans which have agreater number of blades as well as in two-blade and three-blade fans.

I claim:

1. A screw propeller which consists of more than three substantiallyidentical blades of which 0 each diflers in pitch and is spacedangularly around the axis of rotation of the propeller from each of theothers, so disposed that they rotate in substantially the same plane andare arranged around the axis of rotation of the proscrew propeller whichconsists of a plurality of substantially identical blades, so disposedthat they rotate in a single plane positioned between said radiator andengine whereby air is drawn through the former and propelled over thelatter, each of the blades dlflering in angular pitch from each of theothers and spaced angularly around the axis of rotation of the propellerin the numerical order of their pitches, so that in the operation of thepropeller the noise produced as the result of the operation of theengine is minimized. v

WALTER A. GEISE.

